The present invention relates to a method for adapting supplementary equipment, such as automatic answering equipment, intercommunication stations, automatic dialers, and the like, to an analog telecommunications terminal, particularly to a telephone. The present invention further relates to a device for implementing the method.
Telecommunications terminals, in particular simple telephones, frequently need to be upgraded with supplementary equipment, such as automatic answering equipment, intercommunication stations, automatic dialers, etc. This necessitates creating a common connection for both devices while maintaining the functionality of the terminal device, particularly if supplementary equipment, such as an intercommunication station, is to be inserted into the voice-communication path of the terminal which is to be upgraded.
For this, it is known to directly influence the terminal device that is to be upgraded either by using existing modification add-ons of the terminal equipment or, if these are not available, by modifying the internal wiring of the terminal in appropriate fashion. The first approach presupposes that the terminal device to be upgraded has been made ready for modifications with regard to supplementary equipment. This is frequently not the case, particularly when working with simple analog telephones. The second approach presupposes that the user of the terminal either has sufficient technical knowledge to suitably modify the internal wiring of the terminal equipment, or that he or she is willing to engage the services of an expert.
An object of the present invention is, therefore, to delineate a method for adapting supplementary equipment to analog telecommunications terminals, in particular supplementary equipment that has an effect on the voice-communication path of the terminal device to be upgraded, which will obviate the need to intervene in the analog terminal device to be upgraded. It is a further object of the present invention to indicate a device which can be used universally to upgrade terminal equipment with supplementary equipment.
The object of the present invention is achieved by a method for adapting supplementary equipment to an analog telecommunications terminal. The object of the present invention is further achieved by a device for implementing this method.
To achieve the objective, the present invention proposes inserting a supplementary device into the voice-communication path of an analog terminal in such a manner that the operating functions required to set-up or tear-down a connection be able to be executed in the usual manner and that the electrical conditions relating to the telephone network remain unchanged.
For this purpose, the present invention proposes that the mechanical functions, such as entering dial commands on a keypad, be separated from the voice functions of the terminal device by connecting in parallel the analog terminal to be upgraded and the supplementary equipment in the network, without affecting the standardized line termination resistance.
More specifically, to decouple the original voice-communication path from the terminal device, the network access line of the terminal device is first accessed at high resistance, the standardized line termination resistance being maintained. The signal picked up is preferably proportional to the voice signal, which, coming from the telephone network, is transmitted to the terminal device. In- contrast to the normal mode of operation of the terminal equipment, the voice signal transmitted via the network access line directly to the terminal is, in the present invention, not utilized further to realize the voice function.
Rather, the original voice-communication path and the voice input/output unit of the terminal equipment, in particular the telephone handset, remain unused. The handset can be removed.
To realize a new voice-communication path in which the supplementary equipment is able to be easily inserted, the voice signal picked up at high resistance from the network access line, or a signal proportional thereto, is routed to the supplementary equipment and to a voice input/output unit that is electrically separate from the terminal device. Preferably, the voice signal that is picked up is amplified before being launched into the supplementary equipment or voice input/output unit, in order to bring it approximately to the signal level of the signal which was transmitted via the network access line.
Consequently, xe2x80x9cincomingxe2x80x9d voice signals, i.e. those transmitted via the telephone network to the terminal equipment, are routed to the supplementary equipment, as well as to a voice output unit, such as a loudspeaker. The user is able, as usual, to hear the voice signal which has been converted into a sound (audible) signal. In addition, the supplementary equipment can record the voice signals or otherwise influence them, e.g. reproduce them as audible signals via an intercommunication station.
The xe2x80x9coutgoingxe2x80x9d signals, i.e. the voice signals normally entered as sound signals by the user and converted into electronic signals for transmission via the telephone network, are, in the present invention, entered at a voice input unit, which is likewise electrically separate from the terminal to be upgraded. According to the present invention, the original voice-communication path of the terminal equipment also remains unused as far as inputting the voice signals is concerned. However, the terminal to be upgraded is also capable at any time of operating without the supplementary equipment, i.e. the original voice-communication path is not completely deactivated or interrupted. In addition to the voice input unit or alternatively thereto, the supplementary equipment generates an output signal which usually likewise corresponds to spoken speech, e.g. an announcement.
The output signal of the voice input unit and/or of the supplementary equipment is then launched at high resistance into the network access line of the terminal which is to be upgraded, while maintaining the line termination resistance. Preferably, a voltagexe2x80x94controlled power source is used for this purpose. The output signal of the voice input unit and/or the supplementary equipment is used to control the current flow of the power source, whose output is connected to the network access line.
In this manner, therefore, also outgoing signalsxe2x80x94generated both directly by the user or voice input unit and by the supplementary equipmentxe2x80x94are injected as voice signals into the network access line and transmitted via the telephone network.
The terminal equipment is still used to carry out the dialing and other control functionalities. The dialing and control signals are generated as usual by the terminal equipment via keypad input or the like and are routed directly via the network access line to the telephone network. Likewise, dialing and control signals generated by the exchange are sent directly via the network access line to the terminal equipment. This ensures that the user is able to continue to use the terminal equipment in the customary manner. There is no need to modify the terminal""s control system.
In an advantageous further embodiment of the present invention, the functions of the supplementary equipment and/or the voice input/output unit are switched on and off independently of the terminal device""s activity. For this purpose, the voltage level on the network access line is measured and the supplementary equipment and/or the voice input/output unit is activated or deactivated as a function thereof The measurement of the voltage level on the network access line is carried out, for example, by a comparator which accesses the network access line and delivers an output signal if the voltage level rises above or falls below a predetermined threshold. This switching signal is used to switch the supplementary equipment and/or voice input/output unit on and off.
A further refinement of the present invention also provides for drawing upon the activity recognition for economically switching-off the entire power supply.